"It's impossible to keep a secret ... especially one as wonderful as this," the couple and their 10-year-old daughter, Ella Bleu, gushed in a message on the actor's Web site on Tuesday. "We want to be the first to share this great news with everyone that we are expecting a new addition to our family. Love, John, Kelly and Ella."

John, 56, and Kelly, 47, suffered the devastating loss of their son, Jett, in January 2009. The 16-year-old reportedly suffered from a seizure disorder.